Lower Terrace Research Articles

Efecto de los factores climáticos en las fases fenológicas de Mauritia flexuosa Lf. en plantaciones de terraza baja en Ucayali, Perú

The aim of this study was to determine the influence of air temperature and rainfall on the phenological development of Mauritia flexuosa in plantations located in Ucayali, Peru. For this, during a 24-month period, 191 19-year-old palm trees were evaluated, distributed in three plantations established on low terrace soils. The results showed that the 45% of palm trees did not manifest their sexual maturity, meanwhile, 42% and 13% of individuals with male and female sex, respectively, were verified. It was found that the phenological cycle was biannual, with overlapping phenophases and staggered events. In female individuals, maximum flowering was observed in phenophase FLA1 (4-5%) from September to November 2018 and maximum fruiting FRM1 (4-6%) from October 2018 to January 2019; In male individuals, the FLA2 flowering phenophase occurs in two periods between September 2018 and February 2020, meanwhile, the open flower phenophase of both sexes is synchronous in a higher proportion between September and November. It was determined that pluvial precipitation and air temperature (maximum and minimum) did not show correlation (p ≤ 0.05) with the productive phenophases of Mauritia flexuosa. The pluvial precipitation, the maximum temperature and the minimum air temperature showed null association with each one of the phenological phases of the Mauritia flexuosa palm trees during the evaluation period. In order to obtain information for the planning of silvicultural management activities for the conservation of the species, it is recommended to evaluate for more years the influence of climatic elements on the productive development of Mauritia flexuosa.

Monsoonal influences on rip current hazards at recreational beaches along Pahang coastline, Malaysia

Rip current is a type of wave-inducing current that forms nearshore and flows towards the sea. It is a major global hazard in the marine environment that had claimed the lives of hundreds of people due to drowning and recorded thousands of rescue missions around the world. In Malaysia, the Pahang coastline recorded over 30 drowning cases due to rip currents from 2006 to 2018. However, studies on rip current especially on the east coast of Peninsular Malaysia are very limited. Therefore, this study was conducted to classify the beach morphodynamics associated with rip current formations during the southwest monsoon (SWM) and northeast monsoon (NEM) along the Pahang coastline. Five recreational beaches were selected along the Pahang coastline, namely Balok (B1), Batu Hitam (B2), Teluk Cempedak (B3), Sepat (B4), and Air Leleh (B5) as the study site. Sediment samples and beach profile were collected for both monsoonal seasons. It was found that the Pahang coastline was composed of rip-dominant intermediate beaches with several beaches categorised as barred (B), low tide terrace with rip (LTTR), and low tide bar and rip (LTBR). As intermediate beaches are known as rip current dominated beaches, most beaches at Pahang coastline are found to be composed of different risk level of rip current such as high risk (B3 and B5), moderate risk (B1 and B2) and mixed risk (B4). The findings in this study provide useful insights for coastal management planning along the Pahang coastline and the development of beach safety and rescue missions in the event of an emergency related to rip current.

Plant communities with naturalized Elaeagnus angustifolia L. as a new vegetation element in Altai Krai (Southwestern Siberia, Russia)

Elaeagnus angustifolia L. (Russian olive) is a deciduous small tree or large multi-stemmed shrub that becomes invader in different countries all other the world. It is potentially invasive in some regions of Russia. In the beginning of 20th century, it was introduced to the steppe region of Altai Krai (Russia, southwestern Siberia) to prevent wind erosion. During last 20 years, Russian olive starts to create its own natural stands and to influence on native vegetation. This article presents the results of eco-coenotic survey of natural plant communities dominated by Elaeagnus angustifolia L. first described for Siberia and the analysis of their possible syntaxonomic position. The investigation conducted during summer season 2012 in the steppe region of Altai Krai allows revealing one new for Siberia association Elytrigio repentis–Elaeagnetum angustifoliae and no-ranged community Bromopsis inermis–Elaeagnus angustifolia which were included to the Class Nerio–Tamaricetea, to the Order Tamaricetalia ramosissimae. During the study, the following special features of communities have been described: polydominance of herbal layer, anthropogenic and grazing load, variation of the species richness, plant cover and vertical stratification into layers. These peculiarities mostly prove unestablished character of communities, all of them are relatively young (25–30 years). Russian olive shrubberies varies in moisture and saline regime, which connected with their existence in different landforms (lake alluvial plains, gentle slopes of lakes, low lake terraces).

Regionalization of benthic hard-bottom communities across the Pourtalès Terrace, Florida

The Pourtalès Terrace is an exposed hard-bottom platform located south of the Florida Keys in 200–450 m depth with a diverse deep-sea coral ecosystem dominated by stylasterid hydrocorals, octocorals, and sponges that supports recreational and commercial fisheries. Portions of the Terrace have been designated as managed areas in the absence of detailed habitat maps, which hampers identifying ecological benefits derived from such management actions. Here we report analyses of historic Terrace physiographic and geologic data with more recent high-resolution bathymetric and benthic data to statistically derive a benthic community characterization across the Terrace. Multivariate analyses of faunal density from 42 standardized sites showed spatially distinct communities: East Terrace, West Terrace, Upper Terrace Edge, Sinkholes and Lophelia Coral Mound (the southernmost record of this habitat in the continental U.S.). These corresponded to physiographic divisions into an Upper Terrace comprised of Central and Karst-like regions, and Lower Terrace. A detailed description of these communities is provided. This study presents new insights into the Terrace benthic community spatial arrangement and is a necessary step towards facilitating benthic mapping. Our recommendations highlight the information needed for benthic habitat map creation and collecting data to determine if current conservation boundaries match management goals.

Urban planning analysis of the city of Tulun

In June 2019, an environmental and humanitarian disaster occurred in the city of Tulun in the Irkutsk region. The water in the Iya river, on which the city stands, rose 14 meters and flooded 1/3 of the city territory. These were floodplains and low floodplain terraces. More than 15 thd residents lost their homes. Tulun is a small depressive city. There is no work here, starting with “Perestroika”. However, there are natural resources on the basis of which the enterprises of Soviet history successfully developed. And in the current revival of the city’s economy, nature could also help. If cities are designed in accordance with it. After the flooding, a new master plan was developed. Its main provisions include: employment development, urban zoning, and the placement of new residential areas. The problem of the city’s planning framework has not yet been solved. Connections within the city are not well organized.

Epitaxy of boron nitride monolayers for graphene-based lateral heterostructures

Monolayers of hexagonal boron nitride (hBN) are grown on graphite substrates using high-temperature molecular beam epitaxy (HT-MBE). The hBN monolayers are observed to grow predominantly from step edges on the graphite surface and exhibit a strong dependence of the morphology, including the dominant crystallographic edge, of the hBN monolayers, on the growth temperature, as well as systematic variations in growth rate and coverage, and significant differences in the growth at monolayer and multilayer graphite steps. At graphite monolayer steps hBN grows laterally across the surface on the lower terrace, but hBN growth on the upper side of the graphite step is more limited and is nucleated by three-dimensional clusters. Multilayer graphite steps exhibit a much higher density of non-planar hBN aggregates and growth on both the upper and lower terraces occurs. The results show that the hBN monolayer growth edge type, hBN island shape and the presence of hBN aggregates can be controlled in HT-MBE, with the highest quality layers grown at a substrate temperature of about 1390 °C. Sequential HT-MBE growth of hBN, graphene (G) and a second cycle of hBN growth results in the formation of monolayer thick lateral hBN–G–hBN heterostructures, in which a strip of G is embedded between monolayers of hBN.

IDENTIFICATION OF NATURAL RESOURCES IN SOME AREAS OF EL- ISMAILIYA GOVERNORATE USING REMOTE SENSING AND GIS

The current investigation aims to identifying the land and water resources in some areas of Ismailiya governorate. This study covers the soil geomorphological and pedological characteristics including classification, land capability evaluation and assessment the land suitability for certain main crops. The integration of Remote Sensing (RS) and Geographic Information System (GIS) techniques were used to perform this work. The interpretation of satellite image of the study area indicated that, there are six main identified geomorphic units including seven subunits in this area. These units are 1) Depressions, 2) Terraces (Low and High), 3) Basins (over flow basins and Decantation basins), 4) Peneplains (Low and High), 5) Sandy plains (Low, Moderate and High) and 6) Mountain (foot slope and Crest). Twenty soil profiles were selected representing these landforms. The land and site features are observed and registered. Soil profiles were dug and morphologically described. Samples were collected representing the subsequent layers in each profile as well as irrigation water samples were taken for integrated physical and chemical analysis. The studied area has almost flat topography with an elevation between -4 to 134 m. above sea level. The studied soils are deep with well drainage system. These soils have light texture mostly loamy sand with weak granular structure. All of these soils are non-saline to slightly saline and non-sodic having slightly alkaline reaction. These soils are moderately calcareous. Organic matter (OM), cation exchange capacity (CEC) and gypsum are low. These soils have low content of available macro nutrients (N, P and K). All of the studied soils haven’t any diagnostic sub-surface horizons. Therefor these soils are classified under Entisols whether as Typic Torripsaments (89.4%) or Typic Torriorthents (10.6%). The water samples taken from the Low Terraces, Low sandy plains and Peneplains showed a good quality for irrigation purposes. Water samples of the other landforms have moderate to severe salinity, sodicity and chloride hazards. According to the land capability evaluation results, about 25.7% from the studied area was fair (C3) and 74.3% was poor (C4). Land suitability evaluation for sixteen field, vegetables and fruit trees crops indicated that, soils of most the studied landforms except the Low Sandy plains are highly suitable (S1) to marginally suitable (S3) for all studied crops

Human palaeoenvironment in the Upper Kama River basin: experience of reconstruction

Here, we present the results of comprehensive (archaeological and palaeoecological) studies undertaken in 2014–2018 in the basin of the Upper Kama River in the north of Perm Region, eastern part of the East European Plain. The main objects for the research were archaeological sites, primarily their chronological attribution and localization specifics. In total, 100 sites belonging to a wide chronological range from the Mesolithic to the Late Middle Ages were identified in the study area. The palaeochannel method was used to identify the association of the archaeological sites to certain landscapes within the river valley. As a result, five morphologically diverse sectors have been identified. For the reconstruction of natural landscapes and plant communities, palynological and plant macrofossil methods were used. Radiocarbon analysis was used to date these events. The initial human habitation of the Upper Kama region took place in the early Holocene, after the formation of the 2nd and 1st river terraces. The Mesolithic sites have been dated to this period. They were located either on the second river terrace, or on the bedrock valley side. In the Middle Holocene, along with the spread of broad-leaved species in forests, 6th–5th floodplain generations were formed, and the river was characterized by high water content. The Neolithic sites located on the Kama river terraces belong to this period. In the end of the Middle Holocene, the maximum distribution of spruce forests began. This was the time of existence of the Garin Chalcolithic Culture settlements. They were located either on the 4th–5th floodplain generations, or on the bedrock valley side. In the end of the Subboreal and first half of the Subatlantic periods, a key role in the forest stand was played by pine, forming southern taiga light coniferous forests. The water content of the Kama decreased. The sites of the Early Iron Age, located on low terraces or in the floodplain, are dated to this time. In the second half of the Subatlantic period of the Holocene, forests acquired modern mid-taiga appearane, which coincided with the arrival of the medieval population. Medieval hillforts were located on the bedrock valley sides, and the settlements were associated with river terraces, shores of oxbow lakes and floodplains of small rivers.

Updating the significance and paleoclimate implications of magnetic susceptibility of Holocene loessic soils

Mass specific magnetic susceptibility variation with depth along soil profiles developed on loess parent material is one of the most frequently used physical parameter in local, regional and global correlations of loess deposits. It is also utilized as a paleo-precipitation proxy, defined either as absolute difference between susceptibilities of the enhanced B-horizon and parent loess C-horizon; or relative enhancement, using ratios of magnetic parameters. In the present study we compare and analyze the applicability of various approaches in establishment of the empirical relationships between pedogenic magnetic enhancement of Holocene soils from Bulgarian lower Danube area, published data from cCentral and Eastern Europe, and the Chinese loess, and climate parameters – mean annual precipitation (MAP) and mean annual temperature (MAT). Unlike previous studies, which compile data from soils, developed on various parent materials, using maximum magnetic susceptibility of the B-horizon and mean of the C-horizon, we strictly utilize soils, developed on loess material only and consider minimum susceptibility signal in the underlying loess unit. The data analysis shows that minimum magnetic susceptibility of the parent loess exhibits strong relation to climate’s parameters as well. We show that by using minimum magnetic susceptibility of the C-horizon to correct for the detrital input, pedogenic enhancement shows significant multiple correlation with both MAP and MAT. This relationship is different for Chinese and European sites but it is not retained for sites, located at low river terraces, Black sea coast and soils having increased coarse silt and sand content. Grouping the sites according to present day vegetation cover reveals the presence of uniform linear relationship between pedogenic susceptibility enhancement and climate parameters mostly for locations with steppe vegetation, while mixed steppe-forest and forest sites reveal more scattered and steeper relation to MAT and MAP variations.

Late Pleistocene-Holocene characteristics of the North Anatolian Fault at Adapazarı Basin: evidence from the age and geometry of the fluvial terrace staircases

The Late Pleistocene-Holocene evolution of the Adapazarı Basin was investigated using the stratigraphy, geometry, and absoluteluminescence dating of the 4-step fluvial terrace staircases of the Sakarya River. The results revealed that the fluvial cycle was primarily related to relative sea level changes of the Black Sea. The initiation of deposition and the abandonment ages of the terraces indicated relative high stands during marine isotope stage (MIS) 5a (~84-72 ka), 3 (40-30 ka), and 1 (9 ka-recent). The erosional periods in between the terrace steps reflected the response of the Sakarya River to the significantly low stands of the sea. The spatiotemporal position of the high terraces (T4 and T3) yielded an average of 0.78 ± 0.03 mm/year, and uniform and aseismic rock uplift rate for the NW part of the Anatolian Plate bounded by the North Anatolian Fault, which ruptured during the 1999 İzmit earthquake. The lower terrace (T1) was previously used to determine the horizontal slip rate of the Sapanca-Akyazı segment of the earthquake rupture and reported as 16.7 + 3.6/-2.5 mm/year. Further displacement measurements from the surfaces of T2 and T1 yielded a vertical slip rate of 1.49 ± 0.2 mm/year, calculated for the Late Holocene. Extrapolation of these 2 vertical rates to the south and north of the fault zone, in time and space, used in conjunction with the stratigraphy and geometry of the Adapazarı Basin, provided an estimation constraining the timing of the initiation of the fault to 450 ± 50 ka and the total thickness of the basin to ~1100 m.

CO organization at ambient pressure on stepped Pt surfaces: first principles modeling accelerated by neural networks.

Step and kink sites at Pt surfaces have crucial importance in catalysis. We employ a high dimensional neural network potential (HDNNP) trained using first-principles calculations to determine the adsorption structure of CO under ambient conditions (T = 300 K and P = 1 atm) on these surfaces. To thoroughly explore the potential energy surface (PES), we use a modified basin hopping method. We utilize the explored PES to identify the adsorbate structures and show that under the considered conditions several low free energy structures exist. Under the considered temperature and pressure conditions, the step edge (or kink) is totally occupied by on-top CO molecules. We show that the step structure and the structure of CO molecules on the step dictate the arrangement of CO molecules on the lower terrace. On surfaces with (111) steps, like Pt(553), CO forms quasi-hexagonal structures on the terrace with the top site preferred, with on average two top site CO for one multiply bonded CO, while in contrast surfaces with (100) steps, like Pt(557), present a majority of multiply bonded CO on their terrace. Short terraced surfaces, like Pt(643), with square (100) steps that are broken by kink sites constrain the CO arrangement parallel to the step edge. Overall, this effort provides detailed analysis on the influence of the step edge structure, kink sites, and terrace width on the organization of CO molecules on non-reconstructed stepped surfaces, yielding initial structures for understanding restructuring events driven by CO at high coverages and ambient pressure.

Paleomeanders of the Belaya River (the Upper Angara region)

The article presents data on the existence of fragments of the ancient river network in the Belaya River valley (the Angara River basin). We characterize the modern floodplain-terrace complex of the Belaya River, namely the structure of modern floodplains and low terraces, the heights of their basement and morphology, as well as describe the structure of the ancient part of the Belaya River channel. The estimated fragment of the ancient valley of the Belaya River, with a length of 13.6 km, is a macro-bend. The morphometric parameters of the incised meanders of the ancient valley almost two times exceed the modern meanders of free type but are close in their morphometric parameters to modern incised meanders. Based on the morphometric parameters of fragments of the ancient river channel, we calculated the velocities of the paleo-Belaya and compared them with the actual values for the Belaya River. The calculated water flow rates of the ancient channel are 3.7 to 4.5 times higher than the modern parameters. However, these parameters are close to the maximum values during the summer floods. At the next stage of research, we plan to reconstruct the ancient river network of the area by analyzing basal surface maps.

Сообщества с кустарниковыми ивами в подзоне типичных тундр восточноевропейского сектора Арктики

Сообщества с кустарниковыми ивами в подзоне типичных тундр восточноевропейского сектора Арктики

ЭТАПЫ ФОРМИРОВАНИЯ ПЕРВОЙ НАДПОЙМЕННОЙ ТЕРРАСЫ р. ХОЙТО-АГА (ЗАБАЙКАЛЬСКИЙ КРАЙ) В РАЙОНЕ АРХЕОЛОГИЧЕСКОГО ПАМЯТНИКА ВЕРХНЕГО ПАЛЕОЛИТА САХЮРТА–1

Investigation of the 8–10 m high river terrace structure and composition was completed at the archaeological site in the lower Khoito-Aga river. Absolute age of the terrace was estimated using radiocarbon dates of alluvium and buried soils. The results were compared with regional studies of low terraces in the Zabaikalie. The terrace deposits formation stages during the second half of Late Pleistocene and Holocene were identified. The covering genetic complex sediments (2 m) include the Hobdori draw colluvial fan deposits, aeolian, aeolian– deluvial sands and sandy loams, soils. The Сhernozem soil (0.2 m) is recorded in the excavation top. According to archaeological data, it formed during the last ~4.5 kyr. At depths of 100–200 cm, an Early MIS 2 pedocomplex with two humic soil horizons (were dated ~23.4–21.3 kyr BP) was excavated. Soils formed during warm and moist climate stages when rates of exogenous processes were decreased. The completion of alluvium accumulation and terrace escarpment formation were dated ~30–29 kyr BP (MIS 3 and 2 boundary). Interlayed fine–grained and different–grained sands with grus, rubble, gravel alluvial (1.5 m) sediments separated by Late MIS 3 cultural horizons (0.15–0.25 m) with an age of ~ 32.5–31.7 kyr. Within archaeological site Sakhyurta–1 five cultural horizons (CH) were identified with 494 artifacts in total. The cultural horizons 1 and 2 associated with modern soil. The collection of artifacts corresponds to the archaeological sites of the Late Neolithic–Bronze age for Transbaikalia area (4.5–2 kyr BP). Cultural horizon 3 corresponds to the Early MIS 2 pedocomplex (23.4–21.3). СH 4 correlates with terrace alluvium top (31.7–30). СH 5 is associated with alluvial buried soil was dated ~32.5–31.7 kyr BP.

DIVERSIDAD DE AVES EN EL INTERFLUVIO NAPO-PUTUMAYO-AMAZONAS, AL NORTE DE LA AMAZONÍA PERUANA


 
 
 
 
 
 El estudio de los hábitats de la avifauna es fundamental para comprende los patrones de abundancia, diversidad y distribución de las especies. Por ello, se revisó bibliografía y bases de datos generadas en estudios donde se usaron transectos y redes de neblina para conocer la riqueza ornitológica en el interfluvio Napo-Putumayo-Amazonas, su composición por tipos de hábitats, especies amenazadas y principales amenazas. Se analizó la riqueza observada y esperada, así como la similitud entre los hábitats inundables (varillal pantanoso y aguajal mixto) y de tierra firme (colina baja, terraza alta y terraza media). Se compiló el registro de 558 especies, que representan más del 50 % de las especies estimadas para Loreto, siendo los bosques de colina baja los que presentan la mayor riqueza de especies. La composición de especies varía por tipo de hábitat inundable y de tierra firme, pero comparten especies, siendo la terraza media la que alberga especies de bosque inundable y tierra firme. Las familias Thamnophilidae, Tyrannidae y Furnariidae son las que están mejor representadas en todos los hábitats. La avifauna es muy diversa y alberga especies únicas, amenazadas y potenciales para el aviturismo. Lamentablemente, la zona también tiene amenazas que ponen en peligro la supervivencia de las aves, como la pérdida de hábitats por la deforestación, por la agricultura migratoria, cultivo de Erythroxylum coca y/o industria maderera, tráfico de especies y sobrecaza, por lo que es importante implementar planes de manejo de especies, planes de conservación de hábitats prioritarios o planes turísticos que garanticen la conservación de la avifauna.
 
 
 
 
 

MATERIALS FROM RESEARCH OF O. G. SHAPOSHNIKOVA AND D. YA. TELEHIN IN THE STAROBILSK DISTRICT, LUHANSK REGION

MATERIALS FROM RESEARCH OF O. G. SHAPOSHNIKOVA AND D. YA. TELEHIN IN THE STAROBILSK DISTRICT, LUHANSK REGION

Origin of High Friction at Graphene Step Edges on Graphite.

On graphite, friction is known to be more than an order of magnitude larger at step edge defects as compared to on the basal plane, especially when the counter surface slides from the lower terrace of the step to the upper terrace. Very different mechanisms have been proposed to explain this phenomenon, including atomic interactions between the counter surface and step edge (without physical deformation) and buckling or peeling deformation of the upper graphene terrace. Here, we use atomic force microscopy (AFM) and reactive molecular dynamic (MD) simulations to capture and differentiate the mechanisms proposed to cause high friction at step edges. AFM experiments reveal the difference between cases of no deformation and buckling deformation, and the latter case is attributed to the physical stress exerted by the sliding tip. Reactive MD simulations explore the process of peeling deformation due to tribochemical bond formation between the tip and the step edge. Combining the results of AFM experiments and MD simulations, it is found that each mechanism has identifiable and characteristic features in the lateral force and vertical height profiles recorded during the step-up process. The results demonstrate that buckling and peeling deformation of the graphene edge rarely occur under typical AFM experimental conditions and thus are unlikely to be the origin of high friction at step edges in most measurements. Instead, the high step-up friction is due to stick-slip behavior facilitated by the topographical change and atomic interactions between the tip and step edge without deformation of the graphene itself.

CHARACTERISTICES, CLASSIFICATION AND EVALUATION OF SOILS IN THE AREA SOUTHEAST EL-SADAT CITY, MENOUFIA GOVERNORATE, EGYPT

The current work was performed in 2019 aiming to study the geomorphological and pedological characteristics as well as classification and capability evaluation for soils in the area southeastern El-Sadat City, Menoufia governorate, Egypt. The study area is located at the western side of the Nile-Delta in the east of Cairo-Alexandria desert highway adjacent to the Rashid branch of the River Nile, Menoufia governorate, Egypt. The integration of Remote Sensing (RS) and Geographic Information System (GIS) techniques was used to achieve this work. The geomorphic map produced by processing and identifying the Landsat image using RS and GIS technology indicated that,the studied area has three main geomorphic units with different landforms.These three main units are 1) Alluvial Plain includes three landforms namely: High Terraces (17.33% of the studied area), Moderate Terraces (5.87%) and Low Terraces (11.48%); 2) Pediplain with two landforms namely: High Terraces (16.22 %) and Low Terraces (12.47%); 3) as well as Aeolian Plain with three landforms namely: High Terraces (7.08%), Moderate Terraces (4.97%) and Low Terraces (24.58%). Nineteen soil profiles were chosen to represent the different geomorphic and landform units.The land and site features are observed and registered. Thesoil profiles were dug, morphologically described, and then samples were collected representing the subsequent layers in each profile for integrated physical and chemical analyses. Also, irrigation water samples were collected and analyzed especially for land capability evaluation. The studied area has almost flat to slightly undulated topography. Soils were deep to very deep where they were well drained. Most of the soils have gravely sand to gravely loamy sand texture except the soils of low Alluvial plain terraces that have clay loam texture. The analytical data revealed that, the studied soils are slightly to moderately alkaline, mostly non-saline and haven’t sodicity effect. Few parts showed a sodic horizon feature. The soils are slightly to moderately calcareous having Low gypsum and Organic matter contents. Most of the soils haven't any diagnostic horizons, therefore they were classified under Entisols. The few soils having sodic horizon were classified under Aridisols. The land capability evaluation indicated that, most of the studied soils (92.18%) are affiliated to the Fair, C3 class. Rest of the soils are classified either as a Good capability class, C2, (4.52%), or as a Poor capability class, C4 (3.30%).

Direct observation of the Si(110)-(16×2) surface reconstruction by atomic force microscopy.

The atomic arrangement of the Si(110)-(16×2) reconstruction was directly observed using noncontact atomic force microscopy (NC-AFM) at 78 K. The pentagonal structure, which is the most important building block of the reconstruction, was concluded to consist of five atoms, while only four or five spots (depending on tip bias) have been reported with scanning tunneling microscopy (STM). Single atoms were determined to exist near step edges between upper and lower terraces, which have not been reported using STM. These findings are key evidence for establishing an atomic model of the Si(110)-(16×2) reconstruction, which indeed has a complex structure.

A RECENT GEOMORPHIC AND PEDOLOGICAL STUDIES ON MENOUF PROVINCE SOILS, MENOUFIA GOVERNORATE, EGYPT

The current work was performed in 2018 aiming to study the geomorphological and pedological characteristics as well as classification and capability evaluation for soils of Menouf province area, Menoufia governorate, Egypt. The integration of Remote Sensing (RS) and Geographic Information System (GIS) techniques was used to achieve this work. The geomorphic map produced by processing and identifying the Landsat image using RS and GIS technology indicated that, the main landscape unit in the studied area is Alluvial Plain includes nine landforms namely: high terraces (19.4% of the studied area), medium terraces (15.3%), low terraces (24.6%), over flow basin (25.6 %), decantation basin (7.9%) in addition to meandering belt, depression, levee, and island (with small areas). Twenty-four soil profiles were chosen to represent the different landforms.The land and site features are observed and registered. The soil profiles were dug, morphologically described, and then samples were collected representing the subsequent layers in each profile for integrated physical and chemical analyses. The studied area has almost flat topography with deep soil profiles and freely well drained. These soils have loam to sandy clay loam texture with moderate medium sub angular to angular blocky structure. The analytical data revealed that, the studied soils are moderately alkaline, non-saline and haven’t sodicity effect. The soils are slightly calcareous having very slight gypsum content. Organic matter (OM) is lowand decreases with depth. The cation exchange capacity (CEC) is correlated to the fine fractions and OM contents in these soils. The studied soil profiles haven't any diagnostic horizons, therefore they were classified up to sub great group level under Entisols order mainly as Typic Torriorthents. The land capability evaluation indicated that, about 48% of the studied soils have a Good capability class (C2) and the rest (52%) are considered as a Fair (C3) one.